<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Que</title>
  <style>
    html, body {
      margin: 0;
      padding: 0;
    }
    .header {
      width: 100%;
      height: 400px;
      background-image: linear-gradient(to right, #696969, #43696b);

    }
  </style>
</head>
<body>
<header class="header">
  <h1>Que</h1>
</header>

</body>
</html>